状压dp:luogu P2704 [NOI2001]炮兵阵地

https://www.luogu.org/problemnew/show/P2704

知识点：1.滚动数组：取模实现

               2.位运算优先级最低

             顾是if(!(a&b))而不是if(!a&b)

code: 

#include <bits/stdc++.h>
#define N 101
#define M 10
using namespace std;
int n,m;
int tot = 0;
int dp[4][1000][1000],mp[N],state[1000];
int val[1000];
int check(int k)
{
     if(((k&(k<<1))==0)&&((k&(k<<2))==0)&&((k&(k>>1))==0)&&((k&(k>>2))==0))return 1;
     else return 0;
}
int get(int k)
{
    int ans = 0;
    for(int i = 0;i < m;i++)
    {
        if(k&(1 << i))ans++;
    }
    return ans;
}
char ch[N];
int main()
{
    scanf("%d%d",&n,&m);
    for(int i = 1;i <= n;i++)
    {
        scanf("%s",ch);
        for(int j = 0;j < m;j++)
        {
            if(ch[j] == 'H')
            {
                mp[i] = mp[i]|(1 << j);
            }
        }
    }
    for(int i = 0;i <= (1 << m) - 1;i++)
    {
        if(check(i))
        {
            state[++tot] = i;   
            val[tot] = get(i);
            dp[1][0][tot] = val[tot];
        }
    }
    for(int i = 1;i <= tot;i++)
    {
        for(int j = 1;j <= tot;j++)
        {
            if((state[i]&state[j]) == 0&&(state[i]&mp[2]) == 0)
            dp[2][j][i] = max(dp[2][j][i],dp[1][0][j] + val[i]);
        }
    }
    for(int i = 3;i <= n;i++)
    {
        for(int j = 1;j <= tot;j++)
        if((state[j]&mp[i]) == 0)
        for(int k = 1;k <= tot;k++)
        if((state[k]&mp[i - 1]) == 0)
        for(int p = 1;p <= tot;p++)
        if((state[p]&mp[i - 2]) == 0)
        if((state[p]&state[k]) == 0 && (state[k]&state[j]) == 0 && (state[p]&state[j]) == 0)
        dp[i % 3][k][j] = max(dp[i % 3][k][j],dp[(i - 1) % 3][p][k] + val[j]);
    }
    int ans = -1;
    for(int i = 1;i <= tot;i++)
    for(int j = 1;j <= tot;j++)
    ans = max(dp[n % 3][j][i],ans);
    printf("%d",ans);
    return 0;
}

标签：return,int,luogu,状压,NOI2001,P2704,define,1000
来源： https://www.cnblogs.com/xyj1/p/11066306.html